Steffen Braun1, Stefan Schroeder1, Ulrike Mueller1, Robert Sonntag1, Matthias Buelhoff2, Jan Philippe Kretzer3. 1. Laboratory of Biomechanics and Implant Research, Clinic for Orthopedics and Trauma Surgery, Heidelberg University Hospital, Heidelberg, Germany. 2. Clinic for Orthopedics and Trauma Surgery, Heidelberg University Hospital, Heidelberg, Germany. 3. Laboratory of Biomechanics and Implant Research, Clinic for Orthopedics and Trauma Surgery, Heidelberg University Hospital, Heidelberg, Germany. Electronic address: Philippe.Kretzer@med.uni-heidelberg.de.
Abstract
BACKGROUND: Despite the positive results in total shoulder arthroplasties (TSAs), a higher revision rate is documented compared with total hip and knee replacements. Wear is the possible main cause of TSA failure in the long-term. This study investigated the effect of joint kinematics and the influence of the rotator cuff on the polyethylene wear performance in an anatomic TSA. METHODS: Lifting a load of 2 kg with an abduction/adduction of 0° to 90° was simulated for 2 × 106 cycles as a primary motion using a fully kinematic joint simulator. A combined rotation in anteversion-retroversion of ±5° and ±10° was also simulated. The force in the superior-inferior direction and the axial joint compression were applied under force control based on in vivo data of the shoulder. A soft tissue restraint model was used to simulate an intact and an insufficient rotator cuff. RESULTS: The highest wear rate in the intact rotator cuff group was 58.90 ± 1.20 mg/106 cycles with a combined rotation of ±10°. When an insufficient rotator cuff was simulated, the highest polyethylene wear rate determined was 79.67 ± 4.18 mg/106 cycles. CONCLUSIONS: This study confirms a high dependency of the polyethylene wear behavior and dimension on the joint kinematics in total shoulder replacement. This can be explained by an increasing cross-shear stress on the polyethylene component. The results obtained indicate that additional combined kinematics are an indispensable part of wear tests on anatomic shoulder replacements.
BACKGROUND: Despite the positive results in total shoulder arthroplasties (TSAs), a higher revision rate is documented compared with total hip and knee replacements. Wear is the possible main cause of TSA failure in the long-term. This study investigated the effect of joint kinematics and the influence of the rotator cuff on the polyethylene wear performance in an anatomic TSA. METHODS: Lifting a load of 2 kg with an abduction/adduction of 0° to 90° was simulated for 2 × 106 cycles as a primary motion using a fully kinematic joint simulator. A combined rotation in anteversion-retroversion of ±5° and ±10° was also simulated. The force in the superior-inferior direction and the axial joint compression were applied under force control based on in vivo data of the shoulder. A soft tissue restraint model was used to simulate an intact and an insufficient rotator cuff. RESULTS: The highest wear rate in the intact rotator cuff group was 58.90 ± 1.20 mg/106 cycles with a combined rotation of ±10°. When an insufficient rotator cuff was simulated, the highest polyethylene wear rate determined was 79.67 ± 4.18 mg/106 cycles. CONCLUSIONS: This study confirms a high dependency of the polyethylene wear behavior and dimension on the joint kinematics in total shoulder replacement. This can be explained by an increasing cross-shear stress on the polyethylene component. The results obtained indicate that additional combined kinematics are an indispensable part of wear tests on anatomic shoulder replacements.
Authors: Richard S Page; Angela C Alder-Price; Sophia Rainbird; Stephen E Graves; Richard N de Steiger; Yi Peng; Carl Holder; Michelle F Lorimer; Stephen D Gill Journal: Clin Orthop Relat Res Date: 2022-06-28 Impact factor: 4.755
Authors: Stefan Schroeder; Mareike Schonhoff; Maximilian Uhler; Steffen Braun; Sebastian Jaeger; Tobias Renkawitz; Jan Philippe Kretzer Journal: Clin Orthop Relat Res Date: 2022-05-17 Impact factor: 4.755